Emerging pharmaceutical and organic contaminants removal using carbonaceous waste from oil refineries

The occurrence of emerging organic contaminants (EOCs) such as chemicals in personal care products, pharmaceuticals, plasticizers, etc. in surface waters is a growing global concern. The discharge of most EOCs is not regulated, and EOCs have been shown to be toxic to both human and aquatic life even at low concentrations. In this work, acid-leached carbon black waste (LCBW), a carbonaceous residue from petroleum refineries, was investigated as a potential waste-derived adsorbent for the removal of EOCs. Ciprofloxacin hydrochloride, (CIPRO, antibiotic), sulfamethoxazole (SULFA, antibiotic), acetaminophen (ACET, pharmaceutical), bisphenol A (BPA, plasticizer) and N,N-diethyl-3-methylbenzamide (DEET, insect repellent) were chosen as the target EOCs owing to their presence in relatively high concentrations in surface waters as well as in the influent and effluent of wastewater treatment plants. LCBW, with a specific surface area of 409 m²/g, demonstrated 90-99% removal of 10 ppm CIPRO, BPA, and ACET and 70-80% removal of 10 ppm SULFA and DEET in tap water. Adsorption was rapid, particularly for CIPRO, BPA, and ACET, wherein >85% of the adsorption occurred within 1 h of contact time. To illustrate the potential of LCBW as an adsorbent in different physical forms, ∼3 mm spherical beads of LCBW encapsulated within carboxymethyl cellulose matrix were prepared by a facile ionic gelation method and their adsorption performance was demonstrated.